<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>3.用watch实现姓名案例_异步</title>
        <!-- 引入Vue -->
        <script type="text/javascript" src="../../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="demo">
            姓：<input type="text" v-model="firstName"> <br>
            名：<input type="text" v-model="lastName"> <br>
            <span>全名：{{fullName}}</span>
        </div>

        <script type="text/javascript">
            //阻止 vue 在启动时生成生产提示。
            Vue.config.productionTip = false 
            new Vue({
                el:'#demo',
                data:{
                    firstName:'zhang',
                    lastName:'san',
                    fullName:''
                },
                watch:{
                    firstName(value){
                        console.log('--firstName--变化了',value)
                        setTimeout(()=>{
                            this.fullName = value + '-' + this.lastName
                        },1000)
                    },
                    lastName:{
                        immediate:true,
                        handler(value){
                            console.log('--lastName--变化了',value)
                            this.fullName = this.firstName + '-' + value
                        }
                    }
                }
            })
        
        </script>
    </body>
</html>